N-(ar-vinylbenzyl)aziridines

ABSTRACT

NOVEL N-(M OR P-VINYLBENZYL)AZIRIDINES ARE DISCLOSED WHICH CORRESPOND TO THE STRUCTURAL FORMULA   CH2=CH-C6H4-CH2-(2-R,2-R&#39;&#39;-AZIRIDINO)   WHEREIN R AND R7 ARE HYDROGEN OR LOWER ALKYL. THEY ARE HIGHLY REACTIVE DIFUNCTIONAL MONOMERS WHICH CAN BE HOMOPOLYMERIZED OR COPOLYMERIZED TO FORM MANY USEFUL POLYMERS.

United States Patent O Int. Cl. C07d 23/06 US. Cl. 260-239 E 3 'ClaimsABSTRACT OF THE DISCLOSURE Novel N-(m or p-vinylbenzyl)aziridines aredisclosed which correspond to the structural formula wherein R and R arehydrogen or lower alkyl. They are highly reactive difunctional monomerswhich can be homopolymerized or copolymerized to form many usefulpolymers.

BACKGROUND OF THE INVENTION N-Benzylaziridine is conventionally preparedby reacting benzyl chloride or bromide with aziridine (ethylenimine).The process is conducted in a polar solvent (e.g. methanol) and in thepresence of an acid acceptor and/or an excess of aziridine reactant. SeeEthylenimine and Other Aziridines by O. C. Dermer and G. E. Ham,Academic Press, Inc., NY. (1969) pages 125-6.

SUMMARY OF THE INVENTION We have discovered a class of novel compounds.They are N-(m or p-vinylbenzyl)aziridines corresponding to thestructural formula wherein R and R are each independently hydrogen orlower alkyl of from 1 to 4 carbon atoms. Preferably, R is hydrogen and Ris hydrogen, methyl or ethyl. Most preferably, R and R are eachhydrogen.

The novel compounds are conveniently prepared in accordance with theaforementioned process by using as reactants m or p-vinylbenzyl chlorideor bromide and aziridines corresponding to the structural formulawherein R and R have the aforesaid meaning.

Formula H includes aziridine, Z-methylaziridine, 2- ethylaziridine,2-butylaziridine, 2,2'dimethylaziridine, 2,2-

-dibutylaziridine, and the like.

The subject compounds, (I), are highly reactive difunctional monomers.They can be homopolymerized or interpolymerized with other vinylmonomers by addition polymerization reactions to form novel additionpolymers. Such addition polymers are thermally curable. This is a Iceunique and valuable feature which permits the polymers vto be cast asfilms, molded, etc. and subsequently cured by merely heating them to atemperature sufiicient to ringopen the pendant aziridinyl groups. Theminimum temperature is measured by warming the materials until atemperature exotherm is observed and recording the temperature. Thepolymers are thus useful in coating articles with a cured,solvent-resistant coating, in preparing strong films for packaging, inpreparing molded articles, etc.

Alternatively, the novel polymers can be cured by reaction with apolyfunctional curing agent(s) bearing a plurality of groups which arereactive with the pendant aziridinyl groups on the polymer. Suitablesuch compounds include epoxy resins, carboxylated resins-(e.g. carboxylated polybutadiene, etc.), organic or inorganic polyacids (e.g.phthalic, terephthalic, trimesic, trimellitic and phosphoric acid andthe like), anhydrides, mineral acids, Lewis acids, and other suchpolyfunctional materials.

DETAILED DISCLOSURE The above addition polymers are prepared via con- 7ventional techniques. See, for example, Polymer Processes by C. E.Schildknecht, Interscience Publishers, Inc., NY. 1956), Vol. X of theHigh Polymers series, which summarizes the many known types ofpolymerization processes; the disclosure of which is herewithincorporated by reference thereto. The addition polymers vary in lengthfrom dimers to oligomers on up to high molecular weight polymers havinga molecular weight of several thousand or more. It is well known tothose skilled in the art how to obtain addition polymers within aparticular molecular weight range; e.g. by choice of reactiontemperature, time, concentration and type of initiator, etc.

Vinyl monomers which are polymerizable in such addition polymerizationreactions form a known class of compounds. Any monomer from this knowngroup may be interpolymerized with (I) to form a useful polymer whichcan be formed into a useful article.

Suitable such vinyl monomers include vinyl aromatic monomers (e.g.styrene, a-methylstyrene, vinyltoluene, ar-t-butylstyrene,ar-chlorostyrene, ar,ar-dichlorostyrene, ar-bromostyrene,vinylnaphthalene, and the like); conjugated diolefins (e.g. butadiene,2-chloromethylbutadiene, chloroprene, isoprene,2,3-dimethyl-1,3-butadiene, and the like); alkyl, hydroxyal-kyl andamino-alkyl esters of 01,,6- ethylenically unsaturated carboxylic acids(e.g. the methyl, ethyl, propyl, butyl, hydroxyethyl, 2-hydroxypropyl,2-hydroxybutyl, Z-aminoethyl and 2-aminopropyl acrylates, methacrylates,maleates, itaconates and fumarates, and the like); a,B-ethylenica1lyunsaturated carboxamides (e.g. acrylamide, N-methylolacrylamide,methacrylamide, and the like); u,fl-ethylenically unsaturated nitriles(e.g. acrylonitrile, methacrylonitrile, fumaronitrile, and the like);alkenyl esters of aliphatic and aromatic acids (e.g. vinyl acetate,isopropenyl acetate, allyl propionate, vinyl propionate, vinyl benzoate,isopropenyl benzoate, and the like); and other such vinyl monomers.Preferred vinyl monomers are of course styrene, butadiene, isoprene,lower alkyl (14 carbon atoms) acrylates and methacrylates, andacrylonitrile, based on current commercial availability and economics.

The novel addition polymers contain sufiicient amounts of (I) ininterpolymerized form to render the interpolymer thermally curable.Typically, the interpolymers contain at least about 2.5 weight percentof (I) as a practical minimum. The thermally curable addition polymerswhen heated for 30 minutes at C. are insoluble (but may be swelled) intoluene at a 1% by weight concentration level.

The compounds in formula I are also useful in the preparation ofnonaqueous dispersions as taught in two commonly assigned U. S Pat.applications entitled Process for Preparing High Solids Content PolymerLacquer Dispersions by W. A. Crozier and D. H. Klein Ser. No. 246,874and Vinyl Compositions by D. H. Klein Ser. No. 246,875, both submittedApr. 24, 1972.

The following examples further illustrate the invention.

EXAMPLES Example 1 N- p-Vinylb enzyl Aziridine Anhydrous methanol (200ml.), anhydrous potassium carbonate (10.0 g.) and ar-vinylbenzylchloride (approximately 95% para isomer; 0.05 mol.) were charged to apredried reaction vessel equipped with a stirring means and a dryingtube. Aziridine (27.0 ml.; 0.5 mol.) was added dropwise to the stirredreaction mixture. Subsequently, the stirred mixture was maintained atroom temperature for 24 hours. The work up comprised adding adiatomaceous earth filtering aid to the reaction mixture, filtering outthe solids, removing the solvent from the filtrate under reducedpressure and recovering as the pot residue 7.7 g. of crude product as ayellow/orange liquid. The product was purified by distillativetechniques under reduced pressure. The product was thus obtained as awater-white liquid boiling at 50-52 C. at 0.150.20 mm. of Hg pressure.Vapor phase chromatography (VPC) of this fraction showed it to contain85.7% of the desired product. The compound was obtained from the VPCfractionation and its structure confirmed by infrared (IR) analysis,nuclear magnetic resonance (NMR) and elemental analysis.

Example 2 ar-Vinylbenzylaziridine To a 1-liter, S-necked flask equippedwith a mechanical stirrer, reflux condenser and dropping funnel wascharged 86 g. (2.0 mole) of aziridine, 66 g. of 85% powdered KOH (1.0mole) and 400 ml. of benzene. The mixture was stirred and heated toreflux and 76.25 g. (0.5 mole) of ar-vinylbenzyl chloride containing0.1% by weight of p,p'-diphenylphenylene diamine inhibitor was addedover 15 minutes. The ar-vinylbenzyl chloride was an isomeric mixtureconsisting of approximately 6070% meta isomer and 4030% para isomer. Thereaction mixture was then stirred rapidly under reflux for four hours,cooled to room temperature, filtered through a filter cell and thefiltrate concentrated at reduced pressure to give 72.4 g. (91.1%) ofcrude product. This crude product was distilled at reduced pressure togive 63.1 g. (79.4%) of water-white N-ar-vinylbenzylaziridine b.p. 72-73/ 0.6 mm. whose identity was established by IR and NMR. Its purity wasfound to be greater than 99% by vapor phase chromatography on a G.E.silicone column x A") at 200 C. and 60 ml./min. helium flow rate.

Example 3 N- p-Vinylbenzyl) -2-Methylethylenimine The title compound wasprepared in a manner analogous to Example 1. The components werear-vinylbenzyl chloride (approximately 95% para isomer, 0.249 mol.),potassium carbonate (50.0 g.), anhydrous methanol (1000 ml.) and2-methylaziridine (70 ml.; 0.974 mol.). Distillation of the crudeproduct (a brown oil) gave 7.6 g. of a water-white liquid boiling atabout 85 C. under 0.20.3 mm. of Hg pressure. VPC analysis showed thisfraction to contain 87.1% of the desired product. The product wasobtained from the VPC fractionation and its structure confirmed by IR,NMR and elemental analysis.

Example 4 N-(ar-Vinylbenzyl)-2,2-Dimethylethylenimme The title compoundwas prepared in a manner analogous to Example 2. The reactants werear-vinylbenzyl chloride (same meta and para ratio as in Example 2, 0.25mole), 2,2-dimethylethylenimine (1.0 mole), powdered 85% KOH (0.5 mole)and 200 ml. benzene.

The distilled product was obtained in 84.4% yield (based on theory) as awater-white liquid boiling at 8284 C. at 0.7 mm. of Hg.

Example 5 N-(ar-Vinylbenzyl)-2-Ethylethylenimine The title compound wasprepared in a manner analogous to Example 4 except 2-ethylethyleniminewas used in place of 2,Z-dimethylethylenimine. The distilled product wasobtained in 77.4% yield (based on theory) as a water-white liquidboiling at 75-77 C. at 0.4 mm. of Hg.

Example 6 Copolymer of N-(p-VinylbenzyDAziridine and Styrene A solutionof styrene (22.3 g.; 0.214 mol.) and N-(pviny1benzyl)aziridine fromExample 1 (3.4 g.; 85.7% pure; 0.018 mol.) was charged to a nitrogenpurged polymerization vessel along with azobisisobutyronitrile mg). Thevessel was purged with nitrogen for an additional hour, sealed andheated for 33 hours at 61 C. The polymer thus obtained'was purified byprecipitating it from a toluene solution with methanol. The precipitatedpolymer was ground in a high shear blender in the presence of 200 ml. ofmethanol. The ground polymer was collected by filtration, washed withmethanol and dried in a vacuum oven at 40 C. The polymer (14.8 g.) thusobtained was a white hard solid having a 1.04% nitrogen content. Thiscorresponds to a copolymer having 11 styrene units perN-(p-vinylbenzyl)aziridine unit.

A film was cast from a toluene solution of the above copolymer and curedfor 1 hour at 60 C. The cured film was insoluble in toluene and had agood tensile strength.

Various curing agents were added to aliquots of a toluene solution ofthe copolymer and cast as films on glass plates. The results were: (1)Small amounts of glacial acetic acid, levulinic acid, oxalic acid andisophthalic acid and 1,9-nonanedithiol gave films which were partiallysoluble and/or swelled by toluene. (2) Small amounts of oxalyl chlorideand BF -ethearate caused the copolymer to swell and gel immediatelywhile maleic anhydride caused the copolymer to gel slowly as theanhydride dissolved in the medium. (3) An epoxy resin derived fromBisphenol A and epichlorohydrin gave a film which was in soluble intoluene and had good tensile strength. (4) Phenylacetic acid likewisegave a toluene-insoluble film.

All of the films were clear and colorless. Films cast from a toluenesolution of the copolymer without any curing agent were readilyredissolved in toluene.

Example 7 Homopolymer of N-(p-Vinylbenzyl) Aziridine A 1 ml. sample ofthe product of Example 1 containing 2 mg. of azobisisobutyronitrile waspolymerized by heating it at 61 C. for approximately 18 hours andsubsequently at 70 C. for ,9 hours. The polymer thus produced swelled,but did not dissolve, in toluene even after 1 week.

Other monomers as described by (I) above are similarly prepared by usingthe appropriate aziridinyl reagent.

Other addition interpolymers are similarly prepared by using theappropriate comonomer, e.g. methyl methacrylate, t-butylstyrene, etc.

The addition polymers maybe cast as films having desirable properties,such as tensile strength, or molded into useful articles. Wheredesirable, the polymers can be cross-linked by heating or treatment witha suitable curing agent, e.g. epoxy resins, to form insoluble, hardcrosslinked polymers having many uses, e.g. as containers, ice scrapers,etc.

Alternatively, the addition polymers may be used as cross-linking agentsfor epoxy resins, carboxylated polymers (e.g. carboxylatedpolybutadiene), or other polymers bearing a plurality of carboxylic,sulfonic or anhydride groups.

5 We claim: 1. An N-(mor p-vinylbenzyl) aziridine having the structuralformula R R CHz=CH-C5HrCHz-N\l wherein R and R are hydrogen or alkyl offrom 1 to 4 carbon atoms.

2. The compound defined by Claim 1 wherein R is hydrogen and R ishydrogen, methyl or ethyl.

6 3. The compound defined by Claim 1 wherein R and R are each hydrogen.

References Cited UNITED STATES PATENTS 3,637,662 1/1972 Razdan 260239 EALTON D. ROLLINS, Primary Examiner U.S. Cl. X.R.

26080.3 N, 82.1, 85.5 B, 85.7, 86.1 N, 87.5 R, 88.1 PA, 88.3 R

